Cheaters are lost within a false reality they have had to create in order to cheat, continue cheating and justify cheating. They join in unconsciously using cognitive dissonance, dissociation and compartmentalizing to continue cheating, and yet stay with you acting as if they are primarily still committed to the relationship. To a cheater they have to have a justification, and, all too often that justification is a mostly false narrative.
They will say and even appear to be doing the correct thing to throw you off their trail. This is the reason that once cheating is discovered, counseling and or therapy is required to find out what allowed the cheating to happen, and then correct what went wrong. If this is not done and there is no contact with the affair partner, there is not reconciling.
When an innocent person is asked a question concerning if they have done something wrong and they are innocent, the natural response is to emphatically deny wrongdoing. Attempts to avoid answering, getting defensive and refusing to further engage is a cheaters way of avoiding straight up lying. Refusing to answer and stonewalling is actually an answer within itself.
I am no expert as most of are in fact not experts on cheating as well. But if you look up affair fog/limerence you will find certain actions may drive a cheater out of the fog at the least long enough to see what they have wrought upon themselves and their family. Show you are done playing games, put up or shut up, make the decision to kick her to the curb or you leave yourself. Take away all your support, show what what life without you is like.